Whenever a wireless network is initially installed or expanded, various wireless parameters must be tuned to proper values prior to full commercial operation. The tuning of wireless parameters is referred to as radio frequency (RF)network optimization. The RF optimization typically includes adjusting the direction of base station antennas and the transmit power of down-link transmitters.
Wireless service providers often have relied upon a trial-and-error strategy to optimize radio frequency antenna coverage of cells or other geographic areas within a wireless network. The trial-and-error strategy requires repeated measurements at the same locations through iterative test drives until a feasible constellation of the antenna direction for each base station is found. The test drive refers to taking radio frequency measurement samples from a vehicle which is equipped to measure radio frequency parameters versus location while driving through the coverage area of a wireless network. Based on recorded measurements of parameters in a cluster of cells during a test drive, recommendations on adjusting system parameters are established. However, the trial-and-error approach sometimes leads to quality deterioration or service interruption if incorrect recommendations are applied to an operational system. After the recommended changes to system parameters are implemented, another test drive typically is completed to validate system performance. If the latest test drive did not indicate adequate performance, the wireless network or expansion may be delayed from commercial operation, while yet another round of parameter adjustments is followed by a corresponding test drive.
Even if a wireless network timely goes into commercial operation, improper radio frequency optimization may reduce the capacity of a wireless network. Failure to accurately optimize radio frequency coverage may lead to unnecessary expenditures for capital intensive cellular infrastructure. For example, additional channel capacity or additional cell sites, which are not truly needed, may be added to compensate for an incorrectly optimized wireless system.
The trial-and-error approach to optimization wastes valuable time of engineering and technical resources by often entailing iterative or multiple field measurements to obtain an acceptable solution for radio frequency optimization. The repetitive nature of the trial-and-error tends to make such an approach difficult or impractical for handling large networks. Thus, a need exists for improving the accuracy of optimization rather than relying on the time-consuming and happenstance accumulation of empirical data.
As wireless networks evolve from second generation wireless networks to third generation wireless networks, applying trial-and-error techniques for optimization of radio frequency coverage may become outdated because third generation wireless networks are expected to entail significant complexity in the number of variables and permutations associated with antenna radiation patterns. Second generation wireless networks primarily concern varying the antenna direction in the vertical direction, which is commonly known as down-tilt. In contrast, third generation wireless networks are expected to be capable of varying the base station antenna radiation pattern both vertically and horizontally.